In the field of dentistry, it is often necessary to manufacture and install prostheses. These refer to bridges and, dental apparatuses of various types or similar. Prior to the manufacture of these prostheses, it is essential to take an impression of the denture of the patient. This impression makes it possible to subsequently manufacture a dental prosthesis with specific measurements in a laboratory.
For this purpose, the expert uses a device called an impression tray. This is made of a gutter approximately in the shape of a horseshoe and which matches the shape of a dental arch. The dentist fills this gutter with a pasty substance for impression taking. The impression tray is then introduced into the mouth of the patient. The patient bites the paste to leave an impression of the trace of his or her teeth.
To ensure that the impression is usable, all teeth must be correctly pressed into the paste. It is obvious that the dimensions of the impression tray are decisive. They must be adapted to the morphology of the dental arches of the patient.
In order to be able to adapt to the many morphologies in various patients, experts are currently obliged to possess a wide range of impression trays in various sizes. In each case, they must choose the model to be used.
The aim of the invention is to provide a universal impression tray which may be adapted to all dentures.
This universal impression tray must be able to be easily and quickly adapted to all sizes of dentures. This process should not require a specific resource or a specific particular substance, in addition to those constituting the impression tray.
In addition, this impression tray must be easy and inexpensive to manufacture. It must also be simple, rapid and practical to use.
Moreover, it is advantageous that this impression tray can be used in several parts in order to obtain a sectoral impression tray intended for one section of the denture of the patient only.
To solve this technical problem, several previous devices existed in former dentistry.
To adapt to the morphology of the denture of the patient, one of the former techniques involved adjusting the dimensions of an adaptable impression tray to the size of the denture of the patient prior to taking the impression. Another technique consisted in assembling an impression tray comprising several elements so as to be adapted to the size of denture.
With regard to the formation of a sectoral impression tray, the solution usually used involves assembling elements forming the segment side of the impression tray (U.S. Pat. No. 4,145,812 in the name of JAMES F JOHNSON) or using dividable lines in a traditional impression tray of fixed size made of plastic. However, these solutions are seldom compatible with the former techniques allowing for adaptation of the size of the impression tray.
According to the first technique, we could take, for example, the device described in PCT disclosure No. WO 00/09032 published in the name of INTERNATIONAL DENTSPLY Inc. This is a malleable impression tray whose form is adaptable during a preliminary adjustment process. This preliminary process consists of heating the impression tray, which is made of a thermoformable material, stretching it and modelling it in a suitable way. This process then involves cooling the thermoformable material to obtain solidification in the desired configuration. This solidarisation is carried out before filling the impression tray of paste and carrying out the impression-take.
The European patent application No. EP 0074182 published in the name of WAGNER, mentioned a dental impression tray formed by heating deformable thermoplastic material sheet. The conformation of this sheet is carried out on a test model of the edge of the jaw of the patient, followed by cooling in a mainly rigid state.
These two devices cannot be used directly. They require preliminary working according to a long and difficult to apply process. This process requires the use of expensive additional and specific equipment. These devices thus are not suitable for the technical problem raised. They only allow for limited adaptation to varying morphologies. Moreover, they do not allow for the creation of a sectoral impression tray.
The second method of adaptation is illustrated, for example, by the French patent application No. FR 2551654 by DECROB LOUIS. This application describes an adjustable metal impression tray using a bolt or a central rivet. This bolt or rivet will allow for the articulation of the gutter of the impression tray, in two symmetrical parts, using the level of a clevis pin.
Another example is disclosed in the U.S. Pat. No. 5,340,308 issued in the name of JOSEPH F CUKJATI. This patent describes an impression tray made up of several elements assembled in an adjustable way to the size of denture of the patient.
Nevertheless, devices of this type are expensive and not very practical. They must be assembled and mounted using tools before being able to be used. They cannot generally apply to all sizes of denture. They are, moreover, difficult to clean. In addition, they are not designed to be split for sectoral impression trays.
On the contrary, the impression tray described in the invention makes it possible to solve this technical problem in a particularly simple, fast, practical and inexpensive way.